Thirty-five of the best throwers in the country competed in the hammer events, the largest field assembled in Dunedin.
Tavernier, who won the world junior title in Barcelona last year, turned 20 in Dunedin on Friday. She celebrated on Saturday by smashing an 11-year-old Caledonian Ground senior women's hammer record.
The old record of 60.95m with the 4kg implement was set by Tasha Williams (Canterbury) in 2002.
Tavernier beat this with three of her throws, the best being 66.31m. Her other throws over the record were 64.41m and 65.96m in her first competition of the day.
She went even better in the second competition and extended the Caledonian Ground record to 68.44m. Her other legal throws were 64.75m, 63.35m and 67.44m.
Tavernier has been training in Auckland for the past three months with New Zealand specialist throwing coach Didier Poppe.
When she lives in France, she trains by herself in her home town of Annecy.
''I train with a group in Auckland. I like it and don't want to go home,'' Tavernier said.
Tavernier, who broke the New Zealand hammer throw record with 60.03m and extended it to 70.79m last month, is rated highly by Poppe.
''Alex has very good speed in the circle and is one of the fastest girls I have seen,'' he said.
''She looks like a strong girl but is not. If she works hard on her conditioning she has big potential in the hammer throw.
''She is very close to the Olympic qualifying performance and should get to Rio de Janeiro in 2016.''
The other member of Poppe's stable to break a record at the weekend was Matthew Bloxham (Auckland) in the 6kg men's junior hammer throw.
He held the New Zealand junior men's record at 67.36m and extended it by 1.74m. His legal throws were 66.85m, 65.62m, 67.11m and 69.11m.
''It was hard during the competition because the circle was more slippery than I remembered it last year,'' Bloxham said.
''It was difficult to get speed off the back of the circle.''
The other record was thrown by Lauren Bruce (Timaru), who set a Canterbury aged 17 and 18 record with her throw of 60.17m. It was 37cm further than she threw in Dunedin last month and her first throw over 60m.
Todd Bates (Taieri) missed an Otago men's 18 record because his birthday came two weeks early.
Bates (19) beat his own personal-best distance with five of his throws: 53.10m, 53.78m, 53.71m, 53.94m and 55.31m. His last throw beat the men's aged 18 record standard of 55m but it came too late for him.
